The continued development of organic semiconductor materials relies on an understanding of the relationship between optoelectronic properties, molecular structure, and molecular interaction. Several detailed studies of electronic properties in functionalized polyacene materials are presented. A computational model which allows the extraction of charge generation and transport properties from experimental data is developed. Ultrafast charge generation is observed, and the dependence of transient photocurrent data on this charge generation is determined. Greater crystallinity of the donor leads to more efficient ultrafast charge generation, improving device performance. The effect of varying incident laser intensity is used to test multiple transport models. The effect of acceptor addition to the donor material is investigated. New sources for organic materials to test are important to the future of the field, as there is still a great deal of space for improvement in material properties. One source for organic small molecules which is almost unstudied is molecules secreted by wood-eating fungi. Optical and electronic characterisation is performed on xylindein, a fungally-derived molecule, as an example of the interesting properties and challenges which this source of material present.